The invention relates to a flat tube heat exchanger for motor vehicles with the features of the precharacterizing part of claim 1. Such a flat tube heat exchanger is known from the EP-A1-0 656 517.
In the known flat tube heat exchanger, at the end of the flat tube flaps are bent around collars opened up in the form of a tulip of insertion slits of a tube bottom for the flat tubes by means of special pressing tools. It is true that this results in a reliable mounting, but the corrresponding assembly is inconvenient and requires two steps. In the first step, the tube bottom is placed upon the tube-fin-package, the flaps at the tube ends being at the same time bent over the collars opened up in the form of a tulip by means of special pressing tools. In the second step, the cap has to be placed upon the tube bottom.